Water-soluble film

ABSTRACT

A film-forming composition made from a mixture of PVOH, chitosan, an alkali metal or ammonium bisulfite or metabisulfite, and optional ingredients such as plasticizers, antioxidants, UV stabilizers, surfactants, crosslinking agents, lubricants, and extenders, is disclosed. Also disclosed are a method of making a film from the composition, a resulting film, and a packet made from the film and containing a cleaning composition such as a rinse additive. The composition can be formulated to yield an article such as a film which is soluble only below a predetermined pH threshold.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation-in-part of U.S. patent application Ser. No.11/559,262, filed Nov. 13, 2006, and the benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent Application Ser. No. 60/885,838 filedJan. 19, 2007, is hereby claimed. The disclosures of both applicationsare hereby incorporated herein by reference.

BACKGROUND

1. Field of the Disclosure

The disclosure relates generally to water-soluble structures such asfilms. More particularly, the disclosure relates to water soluble-filmswhich are soluble only in particular pH ranges, which find utility inthe packaging of detergent additives such as rinse additives.

2. Brief Description of Related Technology

Water-soluble polymeric films are known in the art and are described inseveral references. Such polymeric films are commonly used in packagingmaterials to simplify dispersing, pouring, dissolving, and dosing amaterial to be delivered. Water-soluble film packages of such polymericmaterials can be directly added to a mixing vessel, advantageouslyavoiding contact with toxic or messy materials, and allowing accurateformulation in the mixing vessel. Soluble pre-measured polymeric filmpouches aid convenience of consumer use in a variety of applications,particularly those involving wash additives. As used hereinafter, rinseadditive refers to those materials which are intended for use, or aremost efficacious in a rinse portion of a wash cycle and are intended toimprove a property, such as the aesthetics, feel, appearance, sanitationor cleanliness of fabrics or wares which can be washed in machinewashing apparatus. Such wash additives are preferably rinse-added afteran alkaline detergent wash has occurred, and include but are not limitedto fabric softeners, brighteners, anti-redeposition agents, bleaches,and surfactant rinse aids for dishwashing. It is desirable to effectuatethe release of the additives during the rinse portion, rather thanduring the wash portion, of the wash cycle. It is further desirable toadd these products initially, at the start of the wash cycle, therebyavoiding the need to monitor the cleaning process and add the additivesat the beginning of the rinse portion of the wash cycle. Polymeric filmsused to contain such additives would have to be insoluble during thewash phase and become soluble during the rinse phase, and solubilitypreferably is triggered by a difference in pH of the wash solution.

SUMMARY

One aspect of the disclosure provides a method of making a water-solublefilm, including the steps of slurrying a PVOH polymer in a diluteaqueous solution of chitosan; adding any optional ingredients to theslurry, including plasticizers, antioxidants, UV stabilizers,surfactants, crosslinking agents, lubricants, and extenders; heating theslurry with agitation to thereby solubilize the PVOH; adding an alkalimetal or ammonium bisulfite or metabisulfite to the solution andoptionally agitating the solution to thereby solubilize the alkali metalor ammonium bisulfite or metabisulfite, cooling the solution; andcasting the solution and drying off solvent to thereby obtain awater-soluble polymer film.

Another aspect of the disclosure provides a water-soluble film includinga mixture of PVOH, chitosan in an amount up to 20 wt %, and an alkalimetal or ammonium bisulfite or metabisulfite.

Still another aspect of the disclosure provides a water-soluble filmincluding a mixture of PVOH, chitosan, and an alkali metal or ammoniumbisulfite or metabisulfite wherein the weight ratio of PVOH to chitosanin a range of about 12:1 to about 3:1.

Yet another aspect of the disclosure provides a sealed packet includinga film according to the disclosure herein.

Further aspects and advantages will be apparent to those of ordinaryskill in the art from a review of the following detailed description,taken in conjunction with the drawings. While the compositions, films,and packets described herein are susceptible of embodiments in variousforms, the description hereafter includes specific embodiments with theunderstanding that the disclosure is illustrative, and is not intendedto limit the invention to the specific embodiments described herein.

BRIEF DESCRIPTION OF THE DRAWING

For further facilitating the understanding of the present invention, onedrawing figure is appended hereto.

FIG. 1 shows a two-compartment pouch made from a film according to thedisclosure herein and a conventional PVOH film and containing an ADWdetergent in one compartment and a rinse additive in the othercompartment.

DETAILED DESCRIPTION

The film-forming composition described herein includes a combination ofpolyvinyl alcohol (PVOH), chitosan, and an alkali metal or ammoniumbisulfite or metabisulfite. The components can be formulated by theteachings herein to create an article, such as film, which is soluble inaqueous solutions having a predetermined pH threshold. Such films findutility in, for example, creation of sealed packets for delayed releaseof cleaning actives or rinse additives such as those found in automaticdishwashing detergent compositions or laundry detergent compositions.The sealed packets can be made from any suitable method, including suchprocesses and features such as heat sealing and adhesive sealing (e.g.,with use of a water-soluble adhesive).

The major components of the composition are PVOH, chitosan, and analkali metal or ammonium bisulfite or metabisulfite. In one type ofembodiment, the PVOH has a degree of hydrolysis of greater than 88%,more preferably at least 92% and more preferably 98% or less, forexample in a range of about 92% to about 98%. In another type ofembodiment, the PVOH is fully hydrolyzed (e.g., 99% to 100%). Themolecular weight of the PVOH is not particularly limited, but a mediummolecular weight PVOH having a 4% aqueous solution viscosity of about 20cps to about 30 cps (e.g., 28 cps) at 20° C. is preferred forprocessability and strength of the resulting film. The PVOH ispreferably present in a range of about 50% by weight, based on the totalweight of the film (wt %) to about 90 wt %, on a dry basis, for exampleabout 60 wt % to about 80 wt %, or about 70 wt %.

Chitosan (poly[-(1,4)-2-amino-2-deoxy-D-glucopiranose]) is a partiallyor fully deacetylated form of chitin, a naturally occurringpolysaccharide present in shellfish, for example. Structurally, chitinis a polysaccharide consisting ofbeta-(1,4)2-acetamido-2-deoxy-D-glucose units, some of which aredeacetylated:

wherein x=0.85-0.95 and y=0.15-0.05, for example. The degree ofdeacetylation usually varies between 8 and 15 percent, but depends onthe species from which the chitin is obtained, and the method used forisolation and purification.

Chitin is not one polymer with a fixed stoichiometry, but a class ofpolymers of N-acetylglucosamine with different crystal structures anddegrees of deacetylation, and with fairly large variability from speciesto species. The polysaccharide obtained by more extensive deacetylationof chitin is chitosan:

wherein x=0.50-0.10, and y=0.50-0.90, for example.

Like chitin, chitosan is a generic term for a group of polymers ofacetylglucosamine, but with a degree of deacetylation of generallybetween 50 and 95 percent. Chitosan is the beta-(1,4)-polysaccharide ofD-glucosamine, and is structurally similar to cellulose, except that theC-2 hydroxyl group in cellulose is substituted with a primary aminegroup in chitosan. The large number of free amine groups (pKa=6.3) makeschitosan a polymeric weak base. Both chitin and chitosan are insolublein water, dilute aqueous bases, and most organic solvents. However,unlike chitin, chitosan is soluble in dilute aqueous acids, usuallycarboxylic acids, as the chitosonium salt. Solubility in dilute aqueousacid is therefore a simple way to distinguish chitin from chitosan.

Chitosan is available in different molecular weights (polymers e.g.,50,000 Daltons (Da); oligomers e.g., 2,000 Da), viscosity grades, anddegrees of deacetylation (e.g., 40% to 98%). Chitosan is generallyregarded as non-toxic and biodegradable. The degree of acetylation has asignificant effect on the amine group pKa, and hence solubilitybehavior, and the rheological properties of the polymer. The amine groupon the mostly deacetylated polymer has a pKa in the range of 5.5 to 6.5,depending on the source of the polymer. At low pH, the polymer issoluble, with the sol-gel transition occurring at approximate pH 7. Bothnatural chitosan and synthetic poly-D-glucosamines are contemplated foruse.

The degree of acetylation of the chitosan will influence the pH value atwhich the film begins to dissolve. As the degree of acetylationincreases, the pH above which the film dissolves increases. The degreeof acetylation of the chitosan is preferably about 70% or less, forexample in ranges such as about 55% to about 65%, or about 60% to about65% (e.g., 64%) to provide a film with a pH solubility trigger of about9.2 or 9.3. This material can be obtained by a reacetylation reaction,using acetic anhydride, of commercially available 85% to 95%deacetylated chitosan in aqueous acetic acid, by methods known in theart. The molecular weight of the chitosan is not particularly limitedbut a weight average molecular weight of about 150,000 Da to about190,000 Da is preferred. Chitosan is preferably present in a range ofabout 1 wt % to about 20 wt %, and the following specific contents arecontemplated: up to 15 wt %, up to 12 wt %, up to 10 wt %, up to 8 wt %,4 wt % to 12 wt %, and 6 wt % to 10 wt %. The weight ratio of PVOH tochitosan is contemplated to be in a range of about 12:1 to about 3:1, orabout 8:1 to about 10:1, for example about 9:1. It is surprising thatuse of such low levels of chitosan can provide the desired pH-triggeringability for dissolving the film.

To determine of the acetylation degree, prepare three solutions ofacetic acid of about 0.01, 0.02 and 0.003 M and a deionized watersample, and measure and record the first derivative spectra from 240 nmto 190 nm. The superposition of the three spectra shows the zerocrossing point for the acid. Prepare four or five reference solutions ofN-acetylglucosamine in the range 0.5 mg to 3.5 mg in 100 ml of 0.01 Macetic acid and record the spectra as before. Superpose all spectrarecorded and the measure the height H (mm) for each referenceconcentration above the zero crossing point. Draw a calibration curve ofH versus concentration of N-acetylglucosamine. Determine the curveequation H=f(C). Dissolve 500 mg of dry chitosan (i.e. previously freezedried) in 50 ml of 0.1 M acetic acid and then dilute to 500 ml withwater. In case the degree of acetylation is high, a further 10-folddilution is necessary. Transfer the solution to a Far-UV cuvette with 10mm path length.

Different spectrophotometers may be used: for instance the BECKMAN DU640, the KONTRON UVIKOV 810 and the PERKIN ELMER 550 SE. Obtain thederived spectra at a light with of 1 nm, a scanning speed of 30 nm/minand a time constant of 4 sec, chart speed 10 cm/min. For degree ofacetylation lower than 0.11, correct the final result with a coefficientdeduced from the correction curve.

Without intending to be bound by any particular theory, it is believedthat the changes in amine group pKa with degree of acetylation ofchitosan are related to charge repulsion. Thus in polymers with lowacetylation, protonation of an amine group reduces the basicity ofneighboring amine groups (lower pKa) because the resultant positivecharges will tend to repel one another. On the other hand, in morehighly acetylated polymers, free amine groups are more isolated from oneanother so that charge repulsion cannot occur. This would give rise togreater basicity (higher pKa) and these groups would be expected tobehave more like those of a typical primary amine.

Further, and without intending to be bound by any particular theory, itis believed that the alkali metal or ammonium bisulfite or metabisulfitein the example described below functions by reacting with terminalaldehyde groups on the PVOH to form hydroxysulfonic acid salt adducts,and so prevents Schiff base reactions between PVOH aldehyde groups andchitosan amine groups. It is posited that such Schiff base formation,which occurs over time in the finished film, represents a type ofcrosslink and it has been observed that, in the absence of an alkalimetal or ammonium bisulfite or metabisulfite, the film gradually losesits water solubility until it is completely insoluble at all pHs inapproximately two weeks.

Accordingly, contemplated as an aspect of the invention is a film orother solid water-soluble article made by mixing an aqueous solution ofPVOH, chitosan, and an alkali metal or ammonium bisulfite ormetabisulfite, and subsequently drying off the water, for example by thespecific process described below. The alkali metal or ammonium bisulfiteor metabisulfite preferably is present in the film in an amount up toabout 1 wt %, for example about 0.01 wt % to about 1 wt %, or morepreferably about 0.02 wt % to about 0.25 wt %. For example, sodiumbisulfite preferably is used in an amount in a range of about 0.02 wt %to about 0.2 wt %, e.g., 0.1 wt %. Put another way, the alkali metal orammonium bisulfite or metabisulfite can be present in an amount up toabout 0.9% based on the weight of the PVOH used in the film, for exampleabout 0.005% to about 0.9%, or 0.006% to about 0.8% depending on thetype of alkali metal or ammonium bisulfite or metabisulfite. Forexample, sodium bisulfite is preferably is used in an amount in a rangeof about 0.01% to about 0.22%, e.g., 0.1%, based on the weight of PVOH.Inclusion of an alkali metal or ammonium bisulfite or metabisulfite in apreferred amount of up to 1 wt % in the film, for example, can provideboth prolonged stability and bleaching/decolorization. As a practicalmatter, the alkali metal or ammonium bisulfite or metabisulfite can beadded in excess of 1% in any amount which does not negatively affect theperformance of the composition (e.g., film-forming ability, tensilestrength, dissolution ability) for a desired application. Accordingly,the amount of alkali metal or ammonium bisulfite or metabisulfite ispreferably about 20 wt % or less, for example 15 wt % or less, 10 wt %or less, 5 wt % or less, or 2 wt % or less.

The film composition and film can contain other auxiliary film agentsand processing agents, such as, but not limited to, plasticizers,lubricants, release agents, fillers, extenders, crosslinking agents,antiblocking agents, antioxidants, detackifying agents, antifoams,nanoparticles such as layered silicate-type nanoclays (e.g., sodiummontmorillonite), bleaching agents (e.g., sodium bisulfite or others),and other functional ingredients, in amounts suitable for their intendedpurpose. The amount of such secondary agents is preferably up to about10 wt %, more preferably up to about 5 wt %, e.g., up to 4 wt %.

Examples of crosslinking agents include, but are not limited to, borax,borates, boric acid, citric acid, maleic acid, oxalic acid, malonicacid, succinic acid, cupric salts, water-solublepolyamide-epichlorohydrin, and combinations thereof. Preferredcrosslinking agents include boric acid and water-solublepolyamide-epichlorohydrin, particularly boric acid. A water-solublepolyamide-epichlorohydrin is available under the trade name POLYCUP 172by Hercules, Inc. of Wilmington, Del. The crosslinking agent preferablyis present in an amount up to about 10 wt %, for example about 0.1 wt %to about 10 wt %, or 0.1 wt % to about 5 wt %, depending on the type ofcrosslinking agent. For example, boric acid preferably is used in anamount in a range of about 0.3 wt % to about 0.7 wt %, e.g., 0.5 wt %.Put another way, the crosslinking agent can be present in an amount upto about 10% based on the weight of the PVOH used in the film, forexample about 0.1% to about 10%, or 0.1% to about 5%, depending on thetype of crosslinking agent. For example, boric acid preferably is usedin an amount in a range of about 0.5% to about 0.9%, e.g., 0.7%, basedon the weight of PVOH.

By incorporating a sodium montmorillonite nanoclay, for example in anamount up to about 10 wt %, together with a crosslinking agent asdescribed herein in the film-forming composition, a completelywater-impermeable PVOH film can be formed that is soluble in hot waterat a predetermined pH.

Embodiments including plasticizers are preferred. Plasticizers include,but are not limited to, glycerin, sorbitol, and2-methyl-1,3-propanediol. Combinations of glycerin and sorbitol arepreferred. In preferred embodiments glycerin is used in an amount fromabout 10 wt % to about 20 wt % or 12 wt % to about 18 wt %, e.g., about15 wt %. In preferred embodiments sorbitol is used in an amount fromabout 1 wt % to about 10 wt % or 2 wt % to about 8 wt %, e.g., about 3wt %.

A film can be made by the composition described herein according to anysuitable method. The following method is preferred: disperse allingredients except PVOH and the alkali metal or ammonium bisulfite ormetabisulfite in a cold solution of chitosan (e.g., 2 wt %), slurry thePVOH in the resulting solution, heat (e.g., to 95° C.) with agitation tosolubilize the PVOH, and then cool to 85° C. Add the alkali metal orammonium bisulfite or metabisulfite after a period of time delay, mix,cast the solution, and dry to yield a film. It will be understood by aperson of ordinary skill in the art that other useful structures can bemade by different operations, such as molding.

It has been found that it is preferable to delay the addition of thealkali metal or ammonium bisulfite or metabisulfite to the solution fora period of between about 2 to about 24 hours, preferably about 4 hoursto about 20 hours, and more preferably about 7 hours to about 20 hoursin order to optimize the wet strength of the film during the wash cycle.It is believed that during this period, some degree of Schiff baseformation takes place in solution which enhances the strength of thefilm via mild crosslinking, but does not unduly compromise its watersolubility.

The resulting film preferably is formulated to be insoluble in highlyalkaline solutions (e.g., pH greater than 9.3, preferably greater than10). The resulting film also preferably has sufficient wet strength towithstand agitation in an automatic washing apparatus for the intendeduse during pre-rinse phases of washing.

Use of a film embodiment according to the description can provide apH-dependent water-soluble film. Use of a film embodiment according tothe description can also provide a pH-dependent, water-soluble releasemeans.

The film is useful for containing a detergent composition comprisingcleaning actives. The cleaning actives may take any form such aspowders, gels, pastes, liquids, tablets or any combination thereof.

Inorganic and organic bleaches are suitable cleaning actives for useherein. Inorganic bleaches include perhydrate salts such as perborate,percarbonate, perphosphate, persulfate and persilicate salts. Theinorganic perhydrate salts are normally the alkali metal salts. Theinorganic perhydrate salt may be included as the crystalline solidwithout additional protection. Alternatively, the salt can be coated.

Alkali metal percarbonates, particularly sodium percarbonate arepreferred perhydrates for use herein. The percarbonate is mostpreferably incorporated into the products in a coated form whichprovides in-product stability. A suitable coating material providing inproduct stability comprises mixed salt of a water-soluble alkali metalsulphate and carbonate. Such coatings together with coating processeshave previously been described in GB-1,466,799. The weight ratio of themixed salt coating material to percarbonate lies in the range from 1:99to 1:9, and preferably from 1:49 to 1:19. Preferably, the mixed salt isof sodium sulphate and sodium carbonate which has the general formulaNa₂SO_(4.n.)Na₂CO₃ wherein n is from 0.1 to 3, preferably n is from 0.3to 1.0 and most preferably n is from 0.2 to 0.5. Another suitablecoating material providing in product stability, comprises sodiumsilicate of SiO₂:Na₂O ratio from 1.8:1 to 3.0:1, preferably 1.8:1 to2.4:1, and/or sodium metasilicate, preferably applied at a level of from2% to 10%, (normally from 3% to 5%) of SiO₂ by weight of the inorganicperhydrate salt, such as potassium peroxymonopersulfate. Other coatingswhich contain magnesium silicate, silicate and borate salts, silicateand boric acids, waxes, oils, and fatty soaps can also be usedadvantageously

Typical organic bleaches are organic peroxyacids including diacyl andtetraacylperoxides, especially diperoxydodecanedioc acid,diperoxytetradecanedioc acid, and diperoxyhexadecanedioc acid. Dibenzoylperoxide is a preferred organic peroxyacid herein. The diacyl peroxide,especially dibenzoyl peroxide, should preferably be present in the formof particles having a weight average diameter of from about 0.1 to about100 microns, preferably from about 0.5 to about 30 microns, morepreferably from about 1 to about 10 microns. Preferably, at least about25% to 100%, more preferably at least about 50%, even more preferably atleast about 75%, most preferably at least about 90%, of the particlesare smaller than 10 microns, preferably smaller than 6 microns.

Further typical organic bleaches include the peroxy acids, particularexamples being the alkylperoxy acids and the arylperoxy acids. Preferredrepresentatives are: (a) peroxybenzoic acid and its ring-substitutedderivatives, such as alkylperoxybenzoic acids, but alsoperoxy-α-naphthoic acid and magnesium monoperphthalate; (b) thealiphatic or substituted aliphatic peroxy acids, such as peroxylauricacid, peroxystearic acid, ε-phthalimidoperoxycaproicacid[phthaloiminoperoxyhexanoic acid (PAP)],o-carboxybenzamidoperoxycaproic acid, N-nonenylamidoperadipic acid andN-nonenylamidopersuccinates; and (c) aliphatic and araliphaticperoxydicarboxylic acids, such as 1,12-diperoxycarboxylic acid,1,9-diperoxyazelaic acid, diperoxysebacic acid, diperoxybrassylic acid,the diperoxyphthalic acids, 2-decyldiperoxybutane-1,4-dioic acid,N,N-terephthaloyldi(6-aminopercaproic acid).

Bleach activators are typically organic peracid precursors that enhancethe bleaching action in the course of cleaning at temperatures of 60° C.and below. Bleach activators suitable for use herein include compoundswhich, under perhydrolysis conditions, give aliphatic peroxoycarboxylicacids having preferably from 1 to 10 carbon atoms, in particular from 2to 4 carbon atoms, and/or optionally substituted perbenzoic acid.Suitable substances bear O-acyl and/or N-acyl groups of the number ofcarbon atoms specified and/or optionally substituted benzoyl groups.Preference is given to polyacylated alkylenediamines, in particulartetraacetylethylenediamine (TAED), acylated triazine derivatives, inparticular 1,5-diacetyl-2,4-dioxohexahydro-1,3,5-triazine (DADHT),acylated glycolurils, in particular tetraacetylglycoluril (TAGU),N-acylimides, in particular N-nonanoylsuccinimide (NOSI), acylatedphenolsulfonates, in particular n-nonanoyl- orisononanoyloxybenzenesulfonate (n- or iso-NOBS), carboxylic anhydrides,in particular phthalic anhydride, acylated polyhydric alcohols, inparticular triacetin, ethylene glycol diacetate and2,5-diacetoxy-2,5-dihydrofuran and also triethylacetyl citrate (TEAC).

Bleach catalysts preferred for use herein include the manganesetriazacyclononane and related complexes (U.S. Pat. No. 4,246,612, U.S.Pat. No. 5,227,084); Co, Cu, Mn and Fe bispyridylamine and relatedcomplexes (U.S. Pat. No. 5,114,611); and pentamine acetate cobalt(III)and related complexes (U.S. Pat. No. 4,810,410). A complete descriptionof bleach catalysts suitable for use herein can be found in WO 99/06521,pages 34, line 26 to page 40, line 16.

A preferred surfactant for use in automatic dishwashing is low foamingby itself or in combination with other components (i.e. sudssuppressers). Preferred for use herein are low and high cloud pointnonionic surfactants and mixtures thereof including nonionic alkoxylatedsurfactants (especially ethoxylates derived from C₆-C₁₈ primaryalcohols), ethoxylated-propoxylated alcohols (e.g., Olin Corporation'sPoly-Tergent® SLF18), epoxy-capped poly(oxyalkylated) alcohols (e.g.,Olin Corporation's Poly-Tergent® SLF18B—see WO-A-94/22800), ether-cappedpoly(oxyalkylated) alcohol surfactants, and blockpolyoxyethylene-polyoxypropylene polymeric compounds such as PLURONIC®,REVERSED PLURONIC®, and TETRONIC® by the BASF-Wyandotte Corp.,Wyandotte, Mich.; amphoteric surfactants such as the C₁₂-C₂₀ alkyl amineoxides (preferred amine oxides for use herein include lauryldimethylamine oxide and hexadecyl dimethyl amine oxide), and alkylamphocarboxylic surfactants such as Miranol™ C2M; and zwitterionicsurfactants such as the betaines and sultaines; and mixtures thereof.Surfactants suitable for use herein are disclosed, for example, in U.S.Pat. No. 3,929,678, U.S. Pat. No. 4,259,217, EP-A-0414 549,WO-A-93/08876 and WO-A-93/08874. Surfactants are typically present at alevel of from about 0.2% to about 30% by weight, more preferably fromabout 0.5% to about 10% by weight, most preferably from about 1% toabout 5% by weight of a detergent composition.

Builders suitable for use herein include water-soluble builders such ascitrates, carbonates, silicate and polyphosphates, e.g. sodiumtripolyphosphate and sodium tripolyphosphate hexahydrate, potassiumtripolyphosphate and mixed sodium and potassium tripolyphosphate salts.

Enzymes suitable herein include bacterial and fungal cellulases such asCAREZYME and CELLUZYME (Novo Nordisk A/S); peroxidases; lipases such asAMANO-P (Amano Pharmaceutical Co.), M1 LIPASE and LIPOMAX(Gist-Brocades) and LIPOLASE and LIPOLASE ULTRA (Novo); cutinases;proteases such as ESPERASE, ALCALASE, DURAZYM and SAVINASE (Novo) andMAXATASE, MAXACAL, PROPERASE and MAXAPEM (Gist-Brocades); α and βamylases such as PURAFECT OX AM (Genencor) and TERMAMYL, BAN, FUNGAMYL,DURAMYL, and NATALASE (Novo); pectinases; and mixtures thereof. Enzymesare preferably added herein as prills, granulates, or cogranulates atlevels typically in the range from about 0.0001% to about 2% pure enzymeby weight of the cleaning composition.

Suds suppressers suitable for use herein include nonionic surfactantshaving a low cloud point. “Cloud point” as used herein, is a well knownproperty of nonionic surfactants which is the result of the surfactantbecoming less soluble with increasing temperature, the temperature atwhich the appearance of a second phase is observable is referred to asthe “cloud point” (See Kirk Othmer, pp. 360-362). As used herein, a “lowcloud point” nonionic surfactant is defined as a nonionic surfactantsystem ingredient having a cloud point of less than 30° C., preferablyless than about 20° C., and even more preferably less than about 10° C.,and most preferably less than about 7.5° C. Typical low cloud pointnonionic surfactants include nonionic alkoxylated surfactants,especially ethoxylates derived from primary alcohol, andpolyoxypropylene/polyoxyethylene/polyoxypropylene (PO/EO/PO) reverseblock polymers. Also, such low cloud point nonionic surfactants include,for example, ethoxylated-propoxylated alcohol (e.g., BASF Poly-Tergent®SLF18) and epoxy-capped poly(oxyalkylated) alcohols (e.g., BASFPoly-Tergent® SLF18B series of nonionics, as described, for example, inU.S. Pat. No. 5,576,281).

Other suitable components herein include cleaning polymers havinganti-redeposition, soil release or other detergency properties.Preferred anti-redeposition polymers herein include acrylic acidcontaining polymers such as SOKALAN PA30, PA20, PA15, PA10 and SOKALANCP10 (BASF GmbH), ACUSOL 45N, 480N, 460N (Rohm and Haas), acrylicacid/maleic acid copolymers such as SOKALAN CP5 and acrylic/methacryliccopolymers. Preferred soil release polymers herein include alkyl andhydroxyalkyl celluloses (U.S. Pat. No. 4,000,093), polyoxyethylenes,polyoxypropylenes and copolymers thereof, and nonionic and anionicpolymers based on terephthalate esters of ethylene glycol, propyleneglycol and mixtures thereof.

Heavy metal sequestrants and crystal growth inhibitors are also suitablefor use in the detergent, for example diethylenetriamine penta(methylenephosphonate), ethylenediamine tetra(methylene phosphonate)hexamethylenediamine tetra(methylene phosphonate), ethylenediphosphonate, hydroxy-ethylene-1,1-diphosphonate, nitrilotriacetate,ethylenediaminotetracetate, ethylenediamine-N,N′-disuccinate in theirsalt and free acid forms.

Suitable for use in a detergent is also a corrosion inhibitor such asorganic silver coating agents (especially paraffins such as WINOG 70sold by Wintershall, Salzbergen, Germany), nitrogen-containing corrosioninhibitor compounds (for example benzotriazole and benzimadazole—seeGB-A-1137741) and Mn(II) compounds, particularly Mn(II) salts of organicligands.

Other suitable components herein include enzyme stabilizers such ascalcium ion, boric acid and propylene glycol.

In one embodiment, use of a film embodiment according to the descriptioncan provide a water-soluble delivery system for a wash additive, whichwill remain insoluble during wash conditions and will rapidly and fullysolubilize during rinse conditions to release a rinse additive.

Use of a film embodiment according to the description can also provide ameans for delivery of a rinse additive, which means may be added duringa wash portion of a wash cycle and which will deliver the rinse additiveduring a rinse portion of a wash cycle.

Suitable rinse additives are known in the art. Commercial rinse aids fordishwashing typically are mixtures of low-foaming fatty alcoholpolyethylene/polypropylene glycol ethers, solubilizers (for examplecumene sulfonate), organic acids (for example citric acid) and solvents(for example ethanol). The function of such rinse aids is to influencethe interfacial tension of the water in such a way that it is able todrain from the rinsed surfaces in the form of a thin coherent film, sothat no water droplets, streaks, or films are left after the subsequentdrying process. A review of the composition of rinse aids and methodsfor testing their performance is presented by W. Schirmer et al. inTens. Surf. Det. 28, 313 (1991). European Patent 0 197 434 to Henkeldescribes rinse aids which contain mixed ethers as surfactants. Rinseadditives such as fabric softeners and the like are also contemplatedand suitable for encapsulation in a film according to the disclosureherein.

The film described herein can also be used to make a packet whichcontains two or more compartments made of the same film or containing acombination with of films of other polymeric materials. Additional filmscan, for example, be obtained by casting, blow-molding, extrusion orblown extrusion of the polymeric material, as known in the art.Preferred polymers, copolymers or derivatives thereof suitable for useas the additional film are selected from polyvinyl alcohols, polyvinylpyrrolidone, polyalkylene oxides, acrylamide, acrylic acid, cellulose,cellulose ethers, cellulose esters, cellulose amides, polyvinylacetates, polycarboxylic acids and salts, polyaminoacids or peptides,polyamides, polyacrylamide, copolymers of maleic/acrylic acids,polysaccharides including starch and gelatine, natural gums such asxanthum and carragum. More preferred polymers are selected frompolyacrylates and water-soluble acrylate copolymers, methylcellulose,carboxymethylcellulose sodium, dextrin, ethylcellulose, hydroxyethylcellulose, hydroxypropyl methylcellulose, maltodextrin,polymethacrylates, and most preferably selected from polyvinyl alcohols,polyvinyl alcohol copolymers and hydroxypropyl methyl cellulose (HPMC),and combinations thereof. Preferably, the level of polymer in the pouchmaterial, for example a PVOH polymer, is at least 60%. The polymer canhave any weight average molecular weight, preferably from about 1000 to1,000,000, more preferably from about 10,000 to 300,000 yet morepreferably from about 20,000 to 150,000. Most preferred pouch materialsare PVOH films known under the trade reference MONOSOL M8630, as sold byMONOSOL LLC of Portage, Ind., US, and PVOH films of correspondingsolubility and deformability characteristics. Other films suitable foruse herein include films known under the trade reference PT film or theK-series of films supplied by Aicello, or VF-HP film supplied byKuraray.

EXAMPLES

The following example is provided for illustration and is not intendedto limit the scope of the invention.

Example 1

A 75 μm film was cast from the following formulation, all components inwt %, solids basis:

TABLE 1 PVOH (MOWIOL 28–99, 99.5% degree of hydrolysis, 72.14 4% sol.visc. 28 cps at 20° C.) glycerin 13.30 chitosan (64% acetylated, MW150,000 to 190,000 Da) 7.97 modified starch 4.00 sorbitol 2.23 sodiumbisulfite 0.15 nonionic surfactant 0.21

A 75 μm film was prepared from this formulation by the followingprocedure: slurry the PVOH in a 2 wt % chitosan solution (cold), add allother ingredients except sodium bisulfite, heat to 95° C. with agitationto solubilize the PVOH, cool to 85° C., add sodium bisulfite after aperiod of seven hours and agitate to solubilize, cast solution, and dry.

The film as described above, along with MONOSOL M-8630 PVOH film, wasused to form 2-compartment packets or pouches containing automatic dishwashing (ADW) detergent and a rinse aid formulation. The packet wasconstructed as shown in FIG. 1 in cross-section, wherein the film 10according to the example enclosed a rinse aid 14 and the conventionalPVOH film 12 enclosed the ADW detergent 18. The packets were tested inan ADW machine where maximum temperatures varied between 40° C. and 65°C. The film according to the example was insoluble and had sufficientwet strength that it did not break or disintegrate during the main washcycle (pH 10.5 to 10.7) and it was soluble in the second rinse cycle (atabout pH 9.3). The film according to the example was stored at ambientconditions in a ZIPLOC polyethylene bag for 21 days, and tested in anADW machine as described above. The film was insoluble and hadsufficient wet strength that it did not break or disintegrate during themain wash cycle and it was soluble in the second rinse cycle. When usinga similarly formulated film except that sodium bisulfite was omitted andthe film was stored at ambient conditions in a ZIPLOC polethylene bagfor 21 days, the film when tested as described above was insolublethroughout the complete wash and rinse cycle. When using a similarlyformulated film except that the PVOH was a partially hydrolyzed PVOH(degree of hydrolysis 88%), the film dissolved during the main washcycle.

Example 2

A 75 μm film was cast from the following formulation, all components inwt %, solids basis:

TABLE 2 PVOH (ELVANOL 70–27, 96% degree of hydrolysis, 71.41 4% sol.visc. 27.5 cps at 20° C.) 2-methyl-1,3-propanediol 13.20 chitosan (64%acetylated, MW 150,000 to 190,000 Da) 7.92 modified starch 3.95 sorbitol3.16 sodium bisulfite 0.15 nonionic surfactant 0.21

A 75 μm film was prepared from this formulation by the followingprocedure: disperse all ingredients except the PVOH and sodium bisulfitein a 2 wt % chitosan solution (cold), slurry the PVOH in the resultingsolution, heat to 95° C. with agitation to solubilize the PVOH, cool to85° C., add the sodium bisulfite after a period of ten hours, mix tosolubilize, cast solution, and dry.

The film as described above, along with MONOSOL M-8630 PVOH film, wasused to form 2-compartment packets or pouches containing automatic dishwashing (ADW) detergent and a rinse aid formulation. The packet wasconstructed as shown in FIG. 1 in cross-section, wherein the film 10according to the example enclosed a rinse aid 14 and the conventionalPVOH film 12 enclosed the ADW detergent 18. The packets were tested inan ADW machine where maximum temperatures varied between 40° C. and 65°C. The film according to the example was insoluble and had sufficientwet strength that it did not break or disintegrate during the main washcycle (pH 10.5 to 10.7) and it was soluble in the second rinse cycle (atabout pH 9.3). The film according to the example was stored at ambientconditions in a ZIPLOC polyethylene bag for 21 days, and tested in anADW machine as described above. The film was insoluble and hadsufficient wet strength that it did not break or disintegrate during themain wash cycle and it was soluble in the second rinse cycle. When usinga similarly formulated film except that sodium bisulfite was omitted andthe film was stored at ambient conditions in a ZIPLOC polyethylene bagfor 21 days, the film when tested as described above was insolublethroughout the complete wash and rinse cycle. When using a similarlyformulated film except that the PVOH had a degree of hydrolysis of 88%,the film dissolved during the main wash cycle.

The foregoing description is given for clearness of understanding only,and no unnecessary limitations should be understood therefrom, asmodifications within the scope of the invention may be apparent to thosehaving ordinary skill in the art.

Throughout the specification, where compositions are described asincluding components or materials, it is contemplated that thecompositions can also consist essentially of, or consist of, anycombination of the recited components or materials, unless describedotherwise.

The practice of a method disclosed herein, and individual steps thereof,can be performed manually and/or with the aid of electronic equipment.Although processes have been described with reference to particularembodiments, a person of ordinary skill in the art will readilyappreciate that other ways of performing the acts associated with themethods may be used. For example, the order of various of the steps maybe changed without departing from the scope or spirit of the method,unless described otherwise. In addition, some of the individual stepscan be combined, omitted, or further subdivided into additional steps.

1. A water-soluble film comprising a mixture of PVOH, chitosan presentin an amount up to 20 wt %, and an alkali metal or ammonium bisulfite ormetabisulfite.
 2. The film of claim 1, wherein the alkali metal orammonium bisulfite or metabisulfite comprises sodium bisulfite.
 3. Thefilm of claim 1, wherein the alkali metal or ammonium bisulfite ormetabisulfite is present in an amount in a range of 0.01 wt % to 1 wt %.4. The film of claim 3, wherein the alkali metal or ammonium bisulfiteor metabisulfite is present in an amount in a range of 0.02 wt % to 0.25wt %.
 5. The film according to claim 1, wherein the PVOH has a degree ofhydrolysis of greater than 88%.
 6. The film according to claim 5,wherein the PVOH has a degree of hydrolysis in a range of 92% to 98%. 7.The film according to claim 1, wherein the chitosan is present in anamount in a range of about 1 wt % to about 20 wt %.
 8. The filmaccording to claim 1, wherein the chitosan has a degree of acetylationin a range of about 55% to about 65%.
 9. The film according claim 8,wherein the chitosan has a degree of acetylation in a range of about 60%to about 65%.
 10. The film according to claim 1, wherein the film issoluble in water having a pH up to about 9.3.
 11. The film according toclaim 1, wherein the film is insoluble in water having a pH greater thanabout 9.3.
 12. The film according to claim 1, further comprising aplasticizer.
 13. The film of claim 12, wherein the plasticizer ispresent in a range of about 10 wt % to about 20 wt %.
 14. The film ofclaim 12, wherein the plasticizer comprises glycerin.
 15. Awater-soluble film comprising 50 wt % to 90 wt % PVOH having a degree ofhydrolysis in a range of 92% to 98%, 1 wt % to 20 wt % chitosan having adegree of acetylation in a range of about 60% to 65%, and 0.01 wt % to 1wt % sodium bisulfite, wherein the film is insoluble in water having apH about 9.3 or greater.
 16. A water-soluble film comprising a mixtureof PVOH, chitosan and an alkali metal or ammonium bisulfite ormetabisulfite wherein the weight ratio of PVOH to chitosan in a range ofabout 12:1 to about 3:1
 17. A sealed packet comprising the film ofclaim
 1. 18. A method of making a water-soluble film, comprising thesteps of: preparing a solution including PVOH polymer and chitosan;adding an alkali metal or ammonium bisulfite or metabisulfite, castingthe solution; and drying off solvent to thereby obtain a water-solublepolymer film.
 19. The method of claim 18, wherein the solution of PVOHand chitosan is prepared by slurrying a PVOH polymer in a dilute, coldaqueous solution of chitosan; adding any optional ingredients to theslurry, including plasticizers, antioxidants, surfactants, lubricants,and extenders; and heating the slurry with agitation to therebysolubilize the PVOH.
 20. The method of claim 18, further comprisingdelaying addition of the alkali metal or ammonium bisulfite ormetabisulfite to the solution including PVOH polymer and chitosan for atime sufficient to increase the wet strength of the resulting film. 21.The method of claim 20, wherein said time is at least two hours.
 22. Afilm made by the method of claim 18.